Strike action by Avanti West Coast train managers is back on after an offer aimed at resolving a dispute over rest day working was rejected.
Members of the RMT union will now walk out on New Year’s Eve and 2 January, as well as every Sunday from 12 January to 25 May.
The union said “sustained strike action” was now “the only way to focus management’s minds on reaching a negotiated settlement”.
Avanti West Coast, which operates trains between London and Scotland and through the West Midlands and north west of England, said the strikes would cause “significant disruption” to customers.
Last week, the RMT called off strikes planned for 22, 23 and 29 December to consider Avanti’s new offer.
But the union said late on Tuesday that 83% of the 400 members involved in the dispute voted against the deal.
The revised offer included higher rest day working payments and more organised allocation of shifts on rest days, it said.
Train managers usually work a 41-hour week but due to staff shortages can be asked to work on their days off. The RMT has argued the current arrangements are “unacceptable”.
Avanti said in response to the latest strikes being announced that it was “disappointed” by the vote against a “very reasonable” revised offer.
“This strike action will cause significant disruption to our customers making journeys on the West Coast Main Line over an extended period,” a statement said.
“We remain open to working with the RMT to resolve the dispute.”
It said it was looking at how the strikes would impact services and would confirm its plans as soon as possible.
Since the middle of 2022, rail travel has been disrupted by industrial action as the RMT and the train drivers’ union Aslef sought better pay and conditions for their members.
The previous Conservative government said changes to working practices were required in return, but Labour secured a deal with the unions after winning the general election.